A business model based 100% on a 3rd party social graph API is not a business model. I hope they can pivot the work they've done to something more standalone.
Why do you think this? It's certainly riskier but there have been many successful companies that start out relying heavily on a 3rd party APIs.
Now if a company patents a specific warhead that only they can make and you decide to make a rocket launcher that is made specifically to launch rockets with those warheads and no other warheads are compatible with your launcher and suddenly the source company decides that their warheads suck anyways, you just lost your business.
My Takarov can fire any type of 7.62×25mm Takarov ammunition, albiet some is better than others. If it could only fire a specific type of surplus ammo that might not longer be available tomorrow, my gun could end up being useless in a blink of an eye.